Apparatus for cooling particulate solids



June 3, 1969 H. L. SMITH, JR 3,447,333

APPARATUS FOR COOLING PARTICULATE SOLIDS Original Filed Jan. 15, 1965 Sheet of s INVENI'OR l/ 1 HORACE L. smw, JR.

ATTORNEYS zymw ww June 3, 1969 H. L. SMITH, JR 3,447,333

APPARATUS FOR COOLING PARTICULATE SOLIDS Original Filed Jan. 15, 1965 Sheet 2 of s //////I ll/ 7 IN VENTOR HORACE 1.. SMITH, JR.

BY Jwywwyww ATTORNEYS 3,447,338 APPARATUS FOR 000mm PARTICULATE' SOLIDS Original Fil'ed Jan. 15, 1965 June 3, 1969 H. L. SMITH, JR

Sheet 3 ore INVENTOR HORACE L sum, JR.

June 3, 1969 H. L. SMITH, JR

APPARATUS FOR COOLING PARTICULAT E SOLIDS Sheet 4 016 Original Filed Jan. 15, 1965 12 3 d 86 0!: n $1 #6:. m )l IIJTIWWI C 3.; n 5% 3m in; m 3i In; L T T 8. SE 85 4 A W B; \A NM. w

INVENTOR HORACE LS ATTORNEYS June 3, 1969 H. L. SMITH, JR

APPARATUS FOR COOLING PARTIGULATE SOLIDS Original Filed Jan. .15, 1965 Sheet 5 15 J. y #7 ,W/ E K Am h o y A SPRAY TIME -SECONDS mvzzmon C16. 6

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BY MWMWMW ATTORNEYS I June 3, 1969 'H. L. SMITH, JR 3,447,338

APPARATUS FOR COOLING PARTICULA'IE SOLIDS Original Filed Jan. 15, 1965 Sheet 6 of s r n N O slams wads SdOLS AV8dS" l N VENTOR HORACE L. 8507', JR.

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ATTOR NE Y5 United States Patent US. Cl. 62-374 11 Claims ABSTRACT OF THE DISCLOSURE Cooling apparatus including a vessel having therein an apertured frustoconical plate for so directing a cooling fluid into a bed of particles in the vessel as to effect circulation of the particles as they are cooled and a system for distributing a liquid onto the circulating particles together with dump mechanism and a control system.

Relation to other applications This application is a division of application No. 425,702 filed Jan. 15, 1965 (now Patent No. 3,345,180).

Background, summary, and objects of the invention The invention disclosed herein relates to the cooling of particulate solids and, more specifically, to novel, improved apparatus for cooling particulate solids.

One particularly important application of the present invention is the cooling of roasted coffee beans. The principles of the present invention will, for the most part, be developed by relating them to this exemplary application of the invention. It is to be understood, however, that this invention has far greater utility. The ensuing discussion of the invention is therefore intended to be illustrative and not limiting with respect to its scope, which is defined only by the appended claims.

At the end of a roast, coffee beans have a temperature throughout of several hundred degrees Fahrenheit. Therefore, unless the roasted beans are cooled rapidly, the residual heat in the beans will prolong the roast even though no external heat is applied to the beans. The result will be a heavy roast which is undesirable because of lower yields and lower soluble solids content and because coifee brewed from the beans will have a poor aroma and bitter taste.

In the past, arrest of the roast has typically been effected by dumping water on the roasted beans as they lie in the roaster or a cooler as described in US. Patent No. 2,278,- 473 issued Apr. 7, 1942, to Musher for Coffee, for example. A major drawback of this method of quenching the roast is the lack of uniformity in the application of the water to the beans. Consequently, the beans are not uniformly cooled and do not have uniform characteristics; and coffee brewed from them is of relatively poor quality.

Another disadvantage of this method of quenching a roast is that heat is inefiiciently transferred from the beans to the cooling fluid. Cooling therefore proceeds slowly and with low efliciency.

Other methods of quenching the roast have heretofore been proposed. For example, US. Patents Nos. 3,122,439 and 2,857,683 suggest fluidizing the roasted coffee with a fluid which will extract heat from the beans. This technique also results in nonuniform cooling because, as pointed out in Patent No. 3,345,180, the particles are virtually stagnant in a fluidized bed; and the fluidizing fluid increases in temperature as it passes upwardly through the bed. Consequently, the particles in the lower part of the bed will be cooled much more rapidly than those in the upper part of the bed.

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A further disadvantage of the fluidized bed method of cooling is that, because the cooling fluid is utilized to fluidize the bed, this fluid must be gaseous. Gases have comparatively poor heat transfer characteristics. Consequently, these processes are relatively inefiicient. Further, because of their poor heat transfer characteristics, gases employed in practical volumes are incapable of arresting the roast with suflicient rapidity to prevent a heavy roast.

US. Patent No. 2,716,936 to Kopf Suggests yet another process for cooling roasted coffee beans. In the Kopf process the beans are cooled with a fluid which includes the volatiles evolved from the coffee beans during the roast. As discussed in Patent No. 3,345,180 I have found that coffees such as Robustas, for example, can be substantially upgraded in quality by driving ofl certain volatile substances during the roast and then removing these substances from the system so that they are not restored to the roasted beans. This benefit is completely lost in the Kopf process in which these volatiles are recirculated into contact with the roasted beans and materially lower their quality.

A further important disadvantage of the Kopf process is that the volatiles Kopf utilizes as a cooling fluid exit from the roaster at a temperature of several hundred degrees Fahrenheit (Kopf speaks of a temperature of 410 To reduce the volume of volatiles necessary for cooling from such temperatures to a sufiiciently low temperature that they could cool the roasted beans to room or a similarly low temperature would be impractical.

I have discovered that the disadvantages of the prior art cooling methods described above can be avoided by employing a novel technique in which the roasted beans are simultaneously agitated or circulated and sprayed with an inert quenching liquid 1 until the temperature of the beans is reduced to a temperature sufliciently low to arrest the roast. While the beans are being sprayed a fluid medium is also preferably circulated through the beans to increase the speed of the quench by absorbing heat from the beans. It is preferred that the fluid medium be at least partially saturated with the quenching liquid to maximize its heat absorbing capacity. After the roast is arrested, cooling of the beans may be continued until the desired final temperature is reached by maintaining the circulation of the beans and continuing to contact them with the fluid cooling medium.

Water is preferably employed as the quenching liquid because of the minimal expense involved. In addition, the use of water as the quenching fluid makes it possible to vary the moisture content of the cooled beans so that this parameter will be at the optimum.

The advantages of the present invention can be realized to a considerable extent by mechanically effecting a continuous circulation of the roasted beans while they are being cooled. I have now discovered, however, that my novel cooling technique can be even more effectively carried out by producing the circulation of the beans by the novel fluid-solids contact technique described in Patent No. 3,345,180. In applying this technique to the cooling of particulate solids, I utilize the cooling medium to fluidize and rotate the bed of roasted beans while they are being sprayed to arrest the roast and during the remainder of the cooling cycle. The fluid medium therefore both produces the necessary circulation of the solids By inert gas, liquid, 'or fluid is meant one which will not adversely affect the quality of the beans or other solids which it comes in contact.

-Sodium bicarbonate or other alkaline materials may be added to water used as a quenching medium in this or any other embodiment of the present invention, if desired, to reduce the acidity of the roasted product although such treat ment may normally not be required in roasting coffee in accord with the principles of the present invention.

3 and also extracts a considerable amount of heat from them.

One advantage of this cooling technique over that disclosed in Patent No. 3,345,180 in which circulation of the beans is effected mechanically is that there is a much more rapid circulation or turnover of the beans being cooled than can be produced by mechanical circulation or agitation. As a result, there is greater uniformity of contact between the beans and the quenching liquid and the fluid cooling medium. Therefore, the beans are more uniformly cooled by application of the principles of the present invention; and the final product is more uniform.

This is extremely important because, as discussed above,

uniformity of the roasted coffee is a major goal in the roasting of coffee.

Uniformity ofcooling is further enhanced in the technique disclosed herein because, due to the rapid circulation of the beans, cooling of all of the beans starts virtually simultaneously and with all of the beans subjected to exactly the same conditions.

Another important advantage of this invention is that, because of the more intimate contact between the beans and the fluid medium, the beans can be cooled to a temperature more closely approaching the ambient temperature of the fluid medium than has heretofore been possible in a cooling cycle of reasonable duration.

Another important advantage of cooling coffee in accord with the principles of the present invention is that there is more intimate contact of the fluid cooling medium and the quenching liquid with the beans. This increases the transfer of heat from the beans to the quenching liquid and fluid medium and therefore reduces the time required to quench the roast. The improved heat transfer characteristics also result in increased efliciency in the cooling process.

An additional important advantage of effecting circulation of beans in the manner just described is that there is a very low presure drop through the bed of beans so that the power required to circulate the fluid medium is, relatively speaking, very low. This can result in substantial cost savings.

A related advantage is that, with the bean surfaces moist, the mass transfer conditions are such that there is a highly efiicient evaporative cooling effect.

Yet another important advantage of cooling roasted coffee in accord with the principles of this invention results from the use of the same fluid medium to fluidize and rotate the bed of beans being cooled and to cool the beans. This simplifies the cooling apparatus and eliminates the energy input required to effect circulation mechanically, reducing the cost of building, operating, and maintaining the cooling apparatus.

Still another important advantage of the present invention is that the liquid sprayed onto the beans is rapidly evaporated as long as the bean temperature is above 212 F. in the case of a water spray, for example. Such evaporation is accomplished by conversion of sensible heat in the beans into latent heat of vaporization, which rapidly reduces the bean temperature by extracting large amounts of sensible heat from the beans.

A further advantage of the present invention is that roasted coffee beans cooled in accord with its principles have a much longer shelf life than beans with the same moisture content cooled by other methods.

Still another advantage of this invention is that beans can be roasted in accord with the principles thereof both at atmospheric and superatmospheric pressures, Cooling techniques and apparatus in accord with the present invention are also much more flexible and versatile than those heretofore known. Other important advantages of the present invention, attributable primarily to the preferred method of effecting circulation of the beans, are identical to those discussed in Patent No. 3,345,180.

From the foregoing, it will be apparent that the principles of the present invention are applicable to the cool- 4 ing of particulate solids generally and are not limited in usefulness to the cooling of roasted coffee beans. Therefore, to the extent that other applications of the present invention are not expressly excluded from the appended claims, they are fully intended to be covered therein.

One important object of the present invention is accordingly the provision of novel improved apparatus for cooling particulate solids, which are particularly applicable to the cooling of roasted coffee beans and the like, but are also applicable to the cooling of other materials.

Other important and related but more specific objects of the present invention include the provision of apparatuses for cooling particulate solids:

(1) Which are capable of more rapidly reducing the temperature of the particulate solids than has heretofore been possible and are therefore capable of substantially reducing the residual-heat induced changes which occur in heretofore known apparatus.

(2) Which, when applied to the cooling of roasted coffee beans and like solids, are capable of materially increasing yields, the quality of the final product, and the soluble solids content in comparison to what is obtainable when heretofore known cooling techniques are employed.

(3) Which are capable of more uniformly cooling the solids and therefore producing a more uniform product than is possible by techniques heretofore known.

(4) Which provide a more efficient transfer of heat from the solids being cooled than is obtained in previously known apparatus.

(5) Which avoid contamination of the solids being cooled with substances such as volatiles driven off in a previous heating step which would adversely affect the properties of the finished product.

(6) In which circulation of the solids being cooled is first effected and in which a quenching liquid is then distributed onto the solids to rapidly decrease the solids temperature and thereby minimize residual-heat induced changes in the solids.

(7) In which a single fluid medium is used both to maintain a continuous rapid circulation of the solids being cooled and to cool the solids.

(8) Capable of cooling solids at lower cost than has heretofore been possible.

(9) Which are capable of utilizing low cost media such as water and air to cool the solids to ambient temperatures, but which can utilize other liquids and fluid media, if desired.

(10) Which, when used for the cooling of roasted coffee beans, produce a product having a longer shelf life than roasted beans of similar moisture content cooled by other methods.

(11) Which can be employed to cool solids both at atmospheric and superatmospheric pressures.

Other objects, further advantages, and additional novel features of the present invention will be apparent from the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing.

Brief description of the drawing In the drawing:

FIGURE 1 is a section through cooling apparatus constructed in accord with the principles of the present invention;

FIGURE 2 is a fragment of FIGURE 1, to an enlarged scale, showing details of a flow control assembly employed in a reaction vessel incorporated in the apparatus of FIGURE 1;

FIGURE 3 is a sectional view, to an enlarged scale, of the lower end of the reaction vessel;

FIGURE 4 is a view similar to FIGURE 1, showing certain components in the reaction vessel positioned to discharge cooled solids from the vessel;

FIGURE 5 is a schematic illustration of a control system for the cooling apparatus of FIGURE 1;

FIGURE 6 is a graph illustrating the effect of spraying a quenching liquid on the solids being cooled in accord with the principles of the present invention;

FIGURE 7 is a reproduction of a temperature record strip chart showing the changes in temperature which occur in the reaction vessel during the cooling cycle; and

FIGURE 8 is a diagrammatic illustration of a second form of cooling apparatus constructed in accord with the principles of the present invention and including a reaction vessel of the type illustrated in FIGURE 1 for cooling particulate solids under pressure.

Detailed description of exemplary embodiments of the invention Referring now to the drawing, FIGURE 1 illustrates apparatus 18 for cooling roasted coffee beans or other particulate solids including a reaction vessel 20 constructed in accord with the principles of the present invention. Reaction vessel 20 has a vertically elongated cylindrical shell 22 which, in one actual embodiment of the present invention, is 70.5 inches in diameter and 90 inches high. In this particular embodiment of the present invention, cooling is effected at atmospheric pressure. Therefore, shell 22 may be fabricated of relatively light gauge sheet metal.

The top wall 26 of shell 22 is provided with an inlet 28 through which the roasted coffee beans enter reaction vessel 20 from a roasting vessel 30 connected to the reaction vessel by a dump conduit 32. A dump valve 34 controls the flow of roasted beans from roaster 30 into reaction vessel 20.

In the lower end of reaction vessel shell 22 is a centrally located aperture or dump opening 36 through which the cooled beans are discharged into a hopper 38. The beans are removed from the hopper as by a pneumatic conveyor 40 for packaging, grinding, or other further treatment.

A second aperture 42, also formed in the lower portion of the reactor shell, accommodates an inlet conduit 44 for a fluid cooling medium. The fluid thus supplied to the reaction vessel passes upwardly through the bed 46 of beans being cooled and is exhausted from the reaction vessel through an outlet conduit 48 extending through an aperture 50 in the top wall 26 of shell 22.

In addition to the components just described, reaction vessel 20 has a dump mechanism 52 for discharging the cooled beans through dump opening 36, a spray system 54 for distributing an inert liquid medium onto the beans in the reaction vessel, and a fluid distributing and directing or flow control assembly 56, which also supports the beans while they are being cooled.

Flow control assembly 56 directs the fluid medium entering the reaction vessel into the bed of beans 46 in such a manner as to fluidize the bed of beans and rotate the fluidized bed by circulating the beans in paths in which they move upwardly in the peripheral regions of the reaction vessel, inwardly toward the center of the reaction vessel in the upper part of bed 46, downwardly in the central regions of the reaction vessel, and outwardly in the lower part of the bed as shown by arrows 57 in FIGURE 2. The circulation of the beams being cooled through the path just described is of extreme importance inasmuch as this pattern of circulation provides intimate, uniform contact between the beams and the fluid medium. Even more important, this pattern of circulation ensures intimate contact and uniform distribution of the inert liquid distributed through spray systern 54 onto the beams to arrest the roast.

Referring specifically to FIGURE 2, flow control assembly 56 includes an outer frustoconical flow plate 58 "In the ensuing detailed description, exemplary embodiments of the present invention will be described exclusively in conjunction with their application to the cooling of roasted coffee beans for the sake of convenience. Such description is intended to be illustrative and not limiting.

bolted or otherwise fixed to the interior of reaction vessel shell 22 and an inner frustoconical flow plate 60 adapted to engage the lower edge of flow plate 58 to support the bed of solids 46. Outer flow plate 58 is constructed to direct 6070% of the fluid entering the reaction vessel through inlet conduit 44 in a generally vertical direction upwardly through the bed of solids 46. In the embodiment of the present invention mentioned above, outer flow plate 58 is fabricated from 0.125 inch thick 304 or 316 stainless steel. The upper surface of flow plate 58 is at an angle of 45 to the horizontal. Its inner edge defines a circular opening 62 which is con centric with the centerline of the reaction vessel and through which inner flow plate 60 extends.

Flow apertures 64 are drilled or otherwise formed in flow plate 58. In the actual reaction vessel just described, there are 6,080 0.136 inch diameter apertures in the outer flow plate. The apertures are drilled at an angle of 45 to the upper surface of the flow plate so that, with the flow plate installed in reaction vessel 20, apertures 64 are vertically oriented. The apertures are arranged in circular and radial rows and are spaced so that the effective hole spacing is uniform over the entire plate. That is, the holes are located so that the product of the radial spacing dimension and the circumferential spacing dimension is essentially constant. In this particular flow plate, the product of the radial and circumferential spacing dimensions is equivalent to 0.45 square inch for each hole location. This provides a uniformly distributed flow through outer flow plate 58.

Inner flow plate 60 is also of frustoconical configuration, but is typically fabricated of somewhat thinner material (0.0625 inch in the illustrated embodiment) than the outer flow plate. At predetermined intervals, louvers 65 are punched or otherwise formed in flow plate 60, providing flow apertures 66 having a width of 0.625 inch and a depth of 0.094 inch through the plate. Louvers 65 direct the treating fluid flowing upwardly in the lower part of the reaction vessel through nozzle plate apertures 66 into a downwardly and outwardly inclined path as shown by arrows 67 in FIGURE 2. In the range of approximately 30-40% of the treating fluid is discharged into the bed of solids being treated through inner flow plate 60. To insure proper rotation of bed 46, louvers 65 are formed so that they will direct the fluid flowing through apertures 66 at an angle of 30 or less to the upper surface of inner nozzle plate 60.

In the embodiment of this invention mentioned previously, the radial distance between adjacent rows of louvers 65 is 1% inches; and the apertures 66 in each row are evenly spaced and are approximately 1% inches apart.

Flow plates of the type desecribed above are disclosed in greater detail in Patent No, 3,345,180 together with other forms of flow plates which may be used if desired instead of those described above. Reference may be made to the latter patent if deemed necessary for a more complete understanding of the present invention.

Like outer plate 58, inner flow plate 60 is oriented with its upper surface 68 at an angle of approximately 45 to the horizontal when installed in reaction vessel 20. The angle the nozzle plates make with the horizontal may be increased but should not be decreased substantially below 30. This is to insure that the angle the upper surfaces of the flow plates make with the horizontal exceeds the angle of repose of the beans or other product being treated. If it does not, the product will not slide off the nozzle plates when dump mechanism 52 is operated to discharge the treated product from the reaction vessel.

For the foregoing it will be apparent that both the flow through apertures 64 in outer flow plate 58 and the flow through apertures 66 in inner flow plate 60 have large velocity components tangential to the fluidized rotatingbed. This provides rapid and complete circula- 7 tion of the solids in the rotating bed through paths of the configuration described above.

Inner nozzle plate 60 is fixed, as by welding, to the lower end of a vertically extending sleeve 7 incorporated in dump mechanism 52. The upper end of sleeve 70 is fixed, as by welding, to a shaft 72 connected to the piston rod 74 of a hydraulic motor 76 supported from the top wall 26 of reaction vessel shell 22 by a framework 78.

In addition to the components just described, dump mechanism 52 includes a conical closure member 80 lslidably mounted on shaft 72 at the lower end thereof by journal bearings 82 and 84 (see FIGURE 3). Journal bearing 82 is fastened, as by brazing, directly to the closure member. Journal bearing 84 is attached to the closure member by a support structure including a circular bar 86 fastened to the closure member and radial bars 88 extending from bar 86 to the journal bearing. Closure member 80 is adapted to engage a circular soft rubber gasket 90 fixed to the bottom wall 92 of reaction vessel shell 22 around dump opening 36 to seal the opening.

To seat closure member 80 against gasket 90, a compression spring 94 is journalled on the shaft, to which one end of the spring is attached. Compression spring 94 biases the closure member against gasket 90 to provide a tight seal. To insure that closure member 80 remains properly seated against gasket 90 during the cooling cycle, compression spring 94 is selected so that the upward force it exerts against the closure member will be greater than the downward force exerted by the gaseous medium in the reaction vessel.

Dump mechanism 52 also includes an inverted, frustoconical guide 96 for directing the cooled beans into d-ump opening 36 when reaction vessel 20 is dumped. The lower inner end of guide 96 is fastened, as by welding or brazing, to the bottom wall 92 of the reaction vessel. At its upper end, guide 96 is supported by vertical standards 98 fastened, at their lower ends, to a reinforcing framework 100 of structural members fixed to the bottom wall of the reaction vessel.

The remaining important feature of reaction vessel 20 is spray system 54, which includes two horizontally disposed circular headers 102 and 104 adjacent the top wall 26 of reaction vessel shell 22. As shown diagrammatically in FIGURE 1, spray header 102 is supported from the top wall 26 of the reaction vessel by a bracket 106 formed of structural members. Located at intervals of typically 45 along header 102 are spray nozzles 108. In one commercial application of the principles of the present invention, this gives a spacing between nozzles of approximately 9 7 inches.

Header 102 is connected to a source of inert liquid medium, generally water, by conduit 110. The water or other liquid flows through the conduit header 102 and out nozzles 108 onto the beans in reaction vessel 20 in the form of a fine mist. As the beans in the reaction vessel are being continuously circulated 'by the gaseous medium supplied through conduit 44 as they are sprayed, there is a uniform application of the liquid medium to the beans and intimate contact of the liquid with the beans. This results in uniform rapid cooling of the beans and a consequent quick arrest of the roast witth he advantages discussed above.

A relatively large volume of water is discharged through nozzles 108 in order to rapidly cool the beans. As the temperature of the beans decreases, it may be desirable to reduce the rate at which the inert liquid medium is added to the beans to insure, for example, that they have the proper moisture content when cooled but do not have wet surfaces. This is accomplished by terminating the flow of liquid medium through nozzles 108 at a predetermined point in the cooling cycle and distributing the remainder of the liquid medium onto the beans through header 104. Header 104 is connected to the source of inert liquid through inlet conduit 112. Header 104 may be provided with the same type of nozzles (not shown) as header 102; or, as an alternative, nozzles may be drilled in the header, In either case, the nozzles are preferably equidistantly spaced around the periphery of header 104 and are oriented to direct the liquid flowing through the header onto the bed 46 of beans being cooled.

In addition to effecting circulation of the beans being cooled in the manner described above, the fluid medium supplied to the reaction vessel is also employed in conjunction With the sprays just discussed to cool the beans. To increase the heat absorbing capacity of the fluid medium an air washer 114, connected by a conduit 116 to the inlet of the blower 118 by which the fluid medium is supplied to the reaction vessel, may be employed. Air washer 114 is of conventional construction. For this reason and because its details are not part of the present invention, it is not considered necessary to describe it in detail herein.

In the actual embodiment of the present invention under discussion, air washer 114 decreases the temperature of the fluid medium (in this case air) from F. to 78 F. and increases its moisture content from 0.0166 pound of water per pound of dry air to 0.0208 pound of water per pound of dry air, materially increasing its capaicty to remove heat from the beans being cooled.

The operation of the cooling apparatus just described can best be summarized by reference to FIGURES 1 and 5, the latter of which is a simplified schematic of the cooling apparatus control system. Referring now to these figures, the cooling apparatus is preferably constructed so that the various steps in the cooling cycle may be controlled manually or automatically. In the ensuing description of a typical cooling cycle, manual operation of the system will be assumed for the sake of convenience.

Manual control is provided by moving selector switches S120, S122, S124, S126, and S127 to the manual position in which contacts A are closed and contacts B open. The switches are shown in this configuration in FIGURE 5. Switch S128 is then closed, energizing relay R130. This, in a manner described in detail in Patent No. 3,345,180, opens dump valve 34 and energizes the dump mechanism (not shown) in roasting vessel 30, discharging a batch of roasted beans from the latter through dump conduit 32 into reaction vessel 20. Switch S128 is then opened, deactivating the dump mechanism and closing dump valve 34.

With the hot roasted beans (typically at a temperature of up to 400 F.) in the cooling apparatus, switch S132 is closed, energizing the motor M134 of blower 118. As described above, this causes blower 118 to supply a fluid medium to the reaction vessel to effect and maintain a circulation of the beans therein and to cool the beans.

As shown in FIGURE 5, a solenoid valve V136 in the inlet conduit to spray system header 102 is connected to the lead to blower motor M134 through a conventional delay type relay R138. Accordingly, after the delay set into relay R138 has elapsed, valve V136 is energized, permitting the inert liquid medium to flow into header 102 and through nozzles 108 onto the circulating beans in reaction vessel 20. This delay is on the order of 40 seconds in one actual cooling system constructed in accord with the principles of this invention. The delay can be varied as desired for different applications of the invention.

In one actual and exemplary embodiment of the present invention, which is designed to cool approximately 750 pounds of roasted coffee beans at a time, the spray is preferably maintained for a period of 2040 seconds and the flow regulated so that at least 0.70 and prefer ably on the order of 0.90 gallon of water per 100 pounds of roasted beans or more is sprayed on them. The spray is then stopped by opening switch S140 to dc-energize solenoid valve V136.

The roasted beans are sprayed in the manner just described to quench arrest the roast at a definite point and to control the moisture content of the roasted beans, as mentioned previously. That the spray just described is effective to rapidly terminate the roast is apparent from FIGURE 7 which shows that, in one exemplary roast, the temperature of the beans being cooled was reduced from 310 F. to 180 F. in approximately 33 seconds. At this lower temperature, the heat remaining in the beans will not cause undesired changes in their characteristics.

Quenching of the roast is extremely important since it has been found that a variation of -10 seconds in a roast having a duration of five to six minutes or longer will aifect the characteristics of the roasted beans to such an extent that the difference in flavor of cofiee brewed from them is readily detectable by the average cofiee drinker. Because of the rapidity with which the beans are cooled by spraying them in the manner described above, such variations in the duration of the roast, caused in heretofore known processes by residual-heat induced changes, are avoided.

In the present invention a spray is particularly eflfective because the fluid medium has a very low velocity above the bed of beans or other solids. Therefore, there is virtually no tendency for the gaseous medium to blow the spray of liquid away from the beans as occurs in some heretofore known cooling apparatus.

As discussed previously, in the conventional process water is dumped on the roasted beans as they lie in a quiescent mass in the bottom of the roasting vessel or a cooler. A typical African bean roasted and quenched in this conventional manner has a yield loss of 15-16 percent. By roasting the same beans in the manner described in Patent No. 3,345,180, but without a quenching spray, this loss is reduced to 11.5-12 percent. By adding a spray of the type described above to add moisture to the roasted beans in a uniformly applied fine mist, the loss is further decreased to less than percent. This gives the process disclosed herein an important economic advantage over the conventional process.

There is another extremely important advantage to quenching the roasted coffee beans in the manner just described. In conventional processes, the shelf life of the roasted product is approximately inversely proportional to its moisture content. That is, as the moisture content is increased, the shelf life of the roasted product is proportionately decreased. Unexpectedly, it has been found that cofiees roasted and then cooled in accord with the present invention have a much longer shelf life than the same coffees roasted and cooled in the conventional manner, even *though those roasted by the present process have a much higher moisture content.

As mentioned briefly above, in some applications of the present invention it may be preferable to diminish the volume of the spray after the beans have been partially cooled. In such cases, the spray through nozzles 108 is interrupted in the manner just described; and switch S142 is closed to energize and thereby open a solenoid valve V144 in the inlet conduit 112 to spray system header 104. This permits the inert liquid to flow through conduit 112 into the spray header and through the nozzles of the latter onto the rapidly circulating beans in reaction vessel 20. Termination of this spray is efiected by opening switch S1 42 to de-energize and thereby close solenoid valve V144.

As discussed above and shown in FIGURE 7, the beans in reaction vessel 20 are typically at a temperature on the order of 180 F. when the distribution of inert liquid onto the beans is terminated. The beans are cooled from this temperature to a temperature typically on the order of 80 F., i.e., room temperature, by continuing the circulation and cooling of the beans with fluid cooling medium supplied to reaction vessel 20 by blower 118. As shown by FIGURE 7, this may take on the order of 5-6 minutes after the spray is terminated for a 750 10 pound batch of beans for which the time-temperature record of FIGURE 7 is typical.

Blower 118 is then stopped by opening switch S132, which de-energizes blower motor M134; and switch S146 is closed. Closing of switch S146 energizes a solenoid R148, admitting an operating fluid to hydraulic motor 76 in a conventional manner (not shown). Upon energization, hydraulic motor 76 moves dump sleeve 70 together with conical inner flow control plate 60 and closure member 80 from the positions shown in FIGURE 1 to the dump positions shown in FIGURE 4. This allows the cooled bean-s in reaction vessel 20 to flow through the annular gap 150 between inner and outer flow plates 58 and 60 into frustoconical guide 96 and out the dump opening 36 in the bottom wall 92 of reaction vessel shell 22 into hopper 38.

Switch 5146 is then opened, de-energizing solenoid R148. This so actuates hydraulic motor 76 as to move dump sleeve 70 and shaft 72 in the opposite, upward direction, engaging inner flow plate 60 with outer flow .plate 58 and seating closure member 80 against the rubber gasket around dump opening 36. Upward movement of shaft 72 and dump sleeve 70 may be terminated in any desired manner such as by the use of limit switches (not shown), for example.

As shown in FIGURE 7, the whole sequence of events in the cooling cycle is typically completed on the order of 6 /2 minutes.

The cooling cycle can be controlled automatically as well as manually. For automatic operation, selector switches S120, S122, S124, S126, and S127 are thrown to Auto so that their A contacts are open and their B contacts are closed. Operation of the various cooling system components is then under the control of a timer T151 through the opening and closing of its contacts T151-1 T151-5. The operation is identical to that described above except that delay relay R138 is not employed in the energization of solenoid valve V13 6 inasmuch as its function is performed by timer T151. Timer T151 may be energized by closing normally open switch S152 although, in actual practice, it will normally be activated by the energization of a relay (not shown) incorporated in a control system such as that shown and described in detail in Patent No. 3,345,180.

As mentioned previously, one of the important features of the novel cooling apparatus 18 described above is that the cooling can be closely controlled to thereby accurately regulate the characteristics of the cooled coffee beans. This is apparent from FIGURE 6 which shows the effect which the duration of the spray has on the final moisture content of the cooled beans and on the temperature difierential between the ambient atmosphere and the beans being cooled when the spray is stopped. As shown by this figure, necessary adjustments in the moisture content of the beans can be made by varying the duration of the spray. The curves in FIGURE 6 are for one particular system in which 750 pound batches of coffee beans are cooled. These curves may vary for other specific applications of the principles of this invention.

This figure also shows that the temperature differential between the ambient atmosphere and the sprayed beans can be reduced to as low as is necessary to prevent residual-heat induced changes in the beans by varying the duration of the spray. It will therefore be apparent that further advantages of the novel cooling apparatus described herein reside in its versatility and the control over the final cooled product that it affords.

In much of the foregoing description, it has been presupposed that cooling apparatus 18 was operated at atmospheric pressure. Coffee roasted for brewing in the conventional manner is normally cooled at atmospheric pressure because beans roasted under superatmospheric pressures do not expand or develop. Therefore, such coffees have a high bulk density in comparison to the conventionally roasted product. Consequently, coffee cooled under pressure has a lower volume/weight ratio than that cooled atmospheric pressure, which is disadvantageous in marketing the roasted colfee.

The disadvantage in cooling coffee at atmospheric pressure is that yields are lower than are obtained by cooling under pressure. Therefore, pressure cooling, is preferably employed for applications such as the manufacture of instant coffee where the higher bulk density of the pressure cooled coffee sent to the extraction columns is not a factor.

Moreover, it has now been found that both the advantages of pressure cooling and development of the beams may be obtained by cooling the beans under pressure, slowly reducing the pressure in the cooling vessel to an intermediate pressure (as discussed in Patent No. 3,345,- 180 this pressure may typically be 2550 p.s.i.g. or as high as 250 p.s.i.g.), and then quickly venting the cooling vessel from the intermediate to atmospheric pressure. This process of cooling provides yields equivalent to those obtained by conventional pressure cooling and, in addition, provides controlled development of the roasted beans.

With the few simple modifications illustrated diagrammatically in FIGURE 8, the cooling apparatus 18 described above may be readily. adapted for cooling roasted beans at superatmospheric pressure. Referring now to the latter figure, the reaction vessel 20 diagrammatically illustrated in this figure may be identical to the reaction vessel 20 described above except for the conventional modifications such as a thicker shell necessary to adapt it to withstand above atmospheric pressures. The reaction vessel is pressurized to the desired cooling pressure (which is preferably generally equal to the roasting pressure which may be as high as on the order of 300 p.s.i. as discussed in Patent No. 3,345,180) by opening a valve V153 in a conduit 154 connecting cooler or reaction vessel 20 to an accumulator 156. Dump valve V157 is then opened, permitting the roasted beans to flow from roaster or reactor 158 to cooler 20 through transfer conduit 160. Valve V157 is then closed, which isolates reactor 158 from cooler 20.

Accumulator 156 is connected through a conduit 162 to a circulation system 164 which includes a booster or circulator 166 and supply and return conduits 168 and 170 connected to cooler 20. Circulation of the cooling fluid is initiated by opening valves V174 and V176 in supply and return conduits 168 and 170, permitting booster 166 to circulate the fluid from conduit 162 through supply conduit 168 into and upwardly through the beans in cooler 20. From cooler 20, the cooling fluid flows through return conduit 170 to exhaust or into a heat exchanger (not shown) where it is cooled so that it may be recirculated.

At the same time that or after the flow of cooling fluid through cooler 20 is initiated, a valve V178 may be opened to slowly vent cooler 20 through a conduit 180 to an intermediate pressure, typically on the order of 25-50 p.s.i.g. When the intermediate pressure is reached, a valve 182 is opened, rapidly venting cooler 20 from the intermediate to atmospheric pressure through a conduit 184. The vent valves may be closed when the pressure in cooler 20 reaches atmospheric to prevent air from entering the cooler, if desired.

The venting of cooling apparatus 18 in the manner described above is employed in the roasting of coffee intended to be brewed by conventional techniques to develop the beans. In the roasting of beans for the manufacture of instant coffee, such venting may be omitted and the coffee cooled to its final temperature at the initial pressure.

In pressure cooling as in cooling at atmosphere pressure, water or other inert liquid is sprayed on the beans in the form of a fine mist as described above to arrest the roast and to control the moisture content of the roasted beans.

After the beans have cooled, a valve V186 in a transfer conduit 188 between cooler 20 and a discharge hopper 190 is opened, and dump mechanism 52 is activated as described above. This permits the cooled beans to flow by gravity from cooler 20 into the discharge hopper, which, if desired, may be pressurized in the manner described in Patent No. 3,345,180.

Valve V186 is then closed and a valve V192 is opened to permit the roasted and cooled beans to flow from discharge hopper 190 through conduit 194 onto a suitable conveyor (not shown).

Many modifications may be made in the illustrated embodiments of the present invention in addition to those discussed above.

As discussed above and from the foregoing description of exemplary applications of the present invention, it will also be readily apparent to those skilled in the arts to which the present invention pertains that its priniciples and the illustrated apparatus can be used to cool panticulate solids other than coffee beans. All such applications of the present invention and apparatus and processes employing its principles are also intended to be covered by the appended claims unless expressly excluded therefrom.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is: 1

1. (a) A reaction vessel configured to contain a bed of particulate solids to be cooled;

(b) means for introducing said particulate solids into said vessel; and (c) means for cooling said solids including means for so introducing a fluid medium having a temperature lower than the temperature of the solids to be cooled into said vessel, directing said medium through the bed of particulate solids contained therein, and discharging said medium from the reaction vessel as to fluidize the entire bed and effect a continuous rapid circulation of at least substantially all of the particles in said vessel through a plurality of successive cycles in each of which said particles are moved upwardly in the peripheral regions of the reaction vessel and migrate downwardly in inner regions thereof to thereby bring said particles into intimate and uniform contact with the fluid medium and accordingly insure rapid and uniform cooling of said solids, said last-named means including at least one frustoconical plate having apertures therethrough for directing said fluid into contact with said solids, said plate being located in the lower reaches of the reaction vessel and having a central opening at the apex thereof, said plate extending downwardly and inwardly from the periphery of the reaction vessel, whereby the apex of said plate is lower than the base thereof and the cooled particulate solids can therefore be discharged through the central opening in the plate by gravity.

2. The apparatus of claim 1, together with means for increasing the moisture content and thereby the heat carrying capacity of said fluid medium.

3. The apparatus of claim 1, together with means for distributing an inert liquid medium onto the circulating particles to rapidly reduce their temperature and thereby minimize residual heat induced changes therein.

4. The apparatus of claim 3, together with control means for first activating said circulation effecting means and then activating said liquid medium distributing means, whereby the circulation of said particles can be established prior to the distribution of said liquid medium thereon to thereby insure the uniform distribution of said medium.

5. The apparatus of claim 3, wherein the liquid medium distributing means comprises a horizontal circular header in and generally concentric with said reaction vessel at the upper end thereof, nozzle means for distributing the liquid medium from the header onto the particulate solids, and means for supplying the liquid medium to said header.

6. The apparatus of claim 3, wherein the means for distributing the inert liquid medium onto the circulating particles comprises a first horizontal circular header in and concentric with said reaction vessel at the upper end thereof, nozzle means for distributing the liquid medium from the first header onto the particulate solids, means for supplying the liquid medium to said header, a second circular header, nozzle means for distributing the liquid medium'from said second header onto the particulate solids, and means for supplying said medium to said second header.

7. In apparatus for cooling particulate solids, the combination of:

(a) a reaction vessel configured to contain a bed of the particulate solids to be cooled;

(b) means for introducing said particulate solids into said vessel; and

() means for cooling said solids and for effecting a continuous movement of the particles in said bed during the cooling of the solids to insure uniform cooling thereof, said last-mentioned means including:

(1) means for introducing a cooling fluid having a temperature lower than that of the particulate solids to be cooled into the lower part of the reaction vessel;

(2) a frustoconical plate having a central opening at the apex thereof and apertures therethrough for directing said fluid into contact with said solids, said plate being located in the lower reaches of the reaction vessel and said apertures having a generally vertical orientation to direct the fluid flowing upwardly through said plate in a generally vertical path, and said plate extending downwardly and inwardly from the periphery of the reaction vessel, whereby the apex of said plate is lower than the base thereof and the cooled particulate solids can therefore be discharged through the central opening in the plate by gravity; and

(3) a second downwardly inclined conical plate adapted to engage the first-mentioned conical plate, whereby said plates provide a support for a bed of said solids, said second conical plate having generally horizontally oriented apertures therethrough for directing the fluid medium flowing through said plate in a generally horizontally path.

8. The combination of claim 7:

(a) wherein one of said conical plates is movable relative to the other and said other plate has a centrally located aperture therein;

(b) wherein the reaction vessel has a dump opening therein below said plates; and

(c) including a closure member configured to close said dump opening and dump mechanism for moving said one plate away from the other said plate and for concomitantly moving said closure member away from said dump opening, whereby the solids will flow between said plates and through the centrally located aperture in said other plate and said dump opening to the exterior of the reaction vessel.

9. The combination of claim 8, wherein said dump mechanism comprises:

(a) a fluid-operated cylinder mounted on said reaction vessel; and

(b) a shaft fixed to a piston rod protruding from said cylinder, said shaft extending into the reaction vessel and said one conical plate and the closure member being supported by said shaft.

10. The combination of claim 8:

(a) wherein said closure member is generally conical and extends through said dump opening, the base of said member being externally of vessel; and including (b) means for biasing said closure member into said dump opening to seat said closure member against the reaction vessel.

11. The combination of claim 7, together with means in said reaction vessel below said conical plates for guiding said solids into said dump opening.

References Cited UNITED STATES PATENTS 3,328,894 7/ 1967 Smith 3457 2,309,036 1/ 1943 Beardsley 241-41 2,648,206 8/1953 Carr 62-63 2,766,534 10/1956 Schaub et al 34l74 X 2,857,683 10/1958 Schytil 3457 2,893,849 7/1959 Krebs 23284 2,925,666 2/1960 Gilmore et a1 34l74 X 3,161,483 12/1964 Morris 3457 3,169,380 2/1965 Callow et a1. 62-57 MEYER PERLIN, Primary Examiner.

WILLIAM E. WAYNER, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,447 ,338 June 3, 1969 Horace L. Smith, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below: In the heading to the printed specification, lines 4 and 5, "Rlchmond, Va., assignor to Hupp Corporation, Cleveland, Ohio,

a corporation of Virginia" should read 301 Lock Lane Richmond, Va. 23226 Column 14 line 1 "horizontally" should read horizontal Signed and sealed this 5th day of May 1970 (SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

